Matrix isolation studies and ab initio calculations of the vibrational spectra of complexes of water with 3-hydroxypyridine

Person, Willis B.; Bene, Janet E. Del; Szajda, W.; Szczepaniak, Krystyna; Szczȩśniak, M.

doi:10.1021/j100160a027

Cited by 38 publications

(20 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The experimental procedure and conditions for preparing the low-temperature matrix and recording the IR spectra with the Nicolet model 740 FTIR spectrometer were the same as those described elsewhere (18). The spectra were studied at a spectral resolution of 1 cm-'.…”

Section: Methodsmentioning

confidence: 99%

Infrared spectra of tautomers and rotamers of 9-methylguanine. An experimental and theoretical study

Szczepaniak¹,

Szczȩśniak²,

Szajda³

et al. 1991

Can. J. Chem.

Self Cite

View full text Add to dashboard Cite

. Both amino-0x0 and amino-hydroxy tautomeric forms of 9-methylguanine have been identified in approximately equal abundance in. infrared studies of these molecules isolated in the hydrophobic environment of an argon matrix at 12 K. The amino-hydroxy tautomer occurs in two different rotamers correlated with the rotation of the OH group. The ratio of concentrations of the two rotamers is sensitive to UV irradiation, and this ratio then relaxes to an equilibrium value after irradiation is stopped. This sensitivity allows us to separate the experimental spectra related to the 0x0 tautomer and to each of the rotamers of the hydroxy tautomer. The relative concentrations of the amino-0x0 and amino-hydroxy tautomers (3) and of the two rotamers (K(h1-h2) = 0.31 & 0.10 in an argon matrix at 12 K and about 30 2 15 in the vapor at 470 K) are estimated from the observed relative infrared absorbances. From these relative concentrations the differences between the free energies of the tautomers (AG47O (0-h) = 0 & 0.5 kJ mol-') and of the two rotamers (AG(h1-h2) = 0.12 ? 0.03 kJ mol-' in the argon matrix at 12 K and AG470 between +2 and -13 kJ mol-' in the vapor at 470 K) have been estimated. The electronic absorption spectrum of 9-methylguanine isolated in the argon matrix at 12 K and the effect of brief ultraviolet irradiation on it have also been studied. In an effort to interpret the experimental results, ab initio calculations of the infrared spectra have been made for 9-methylguanine at the 3-21G//3-21G level. Comparison with the experimental spectra is of some help with the assignment of the infrared spectra for the different tautomers.Key words: 9-methylguanine, tautomerism, infrared and ultraviolet spectra, matrix isolation, ab initio calculation On a aussi CtudiC le spectre d'absorption Clectronique de la 9-mtthylguanine isolCe dans la matrice d'argon B 12 K ainsi que l'effet d'une brkve irradiation avec de I'ultraviolet. Dans le but dlinterprCter les rCsultats exptrimentaux, on a effectuC des calculs ab initio au niveau 3-21G//3-21G des spectres infrarouges de la 9-mtthylguanine. Une comparaison des rCsultats de ces calculs avec les spectres experimentaux est utile pour attribuer les spectres infrarouges des divers tautomkres. Mots clks : 9-mkthylguanine, tautomine, spectres infrarouge et ultraviolet, isolement dans une matrice, calculs ab initio.[Traduit par la rCdaction]

show abstract

Section: Methodsmentioning

confidence: 99%

Infrared spectra of tautomers and rotamers of 9-methylguanine. An experimental and theoretical study

Szczepaniak¹,

Szczȩśniak²,

Szajda³

et al. 1991

Can. J. Chem.

Self Cite

View full text Add to dashboard Cite

show abstract

“…*Denotes water vibrations. 32,33 Other theoretical models predict neither the frequencies nor the relative intensities of the experimental spectra correctly. In particular, differences between calculated and experimental values are most often found for groups involved in the H-bonding.…”

Section: Ir Spectra Of Salicylhydroxamic Acid In Argon Matrixmentioning

confidence: 99%

“…*Denotes water vibrations. 32,33 sha irradiated at wavelengths o320 nm and additionally, at wavelengths o230 nm are given in Figs. 3 and 4.…”

Section: Photolysis Of Salicylhydroxamic Acidmentioning

confidence: 99%

Matrix-isolation and computational study of salicylhydroxamic acid and its photochemical degradation

Kaczor

Szczepański

Vala

et al. 2005

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

The IR absorption spectrum of salicylhydroxamic acid (sha) isolated in an argon matrix at 12-21 K has been recorded. Calculations of all the possible entgegen and zusammen keto conformers of sha have been performed at the B3LYP/6-311++G(d,p) level of theory. The computed energies, optimized structures, and relative abundances show that sha exists in the matrix as the z,z,z,z-conformer [relative to the C-O(-H), C-C(-N), C-N and N-O bonds, respectively] and is stabilized by two intramolecular H-bonds. Photofragmentation of the compound in matrix and methanol-water solution has been obtained by irradiation with visible and ultraviolet light. o-Hydroxyphenylisocyanate is the main photolysis product in an argon matrix, while salicylamide is the primary photolysis product in methanol-water solution.

show abstract

“…6 Quite frequently (see, for example, Refs. 4,7–14) pyridinol/pyridinone tautomerization is used as a model for biological systems, a key feature of which is that the relative energies of the OXO and HYDROXY tautomers are very similar so that large energy penalties are not encountered.…”

Section: Introductionmentioning

confidence: 99%

Chemical Control of Tautomerization‐Based Molecular Electronic and Color Switches

Reimers

Hall

Hush

et al. 1998

Annals of the New York Academy of Sciences

View full text Add to dashboard Cite

Many schemes which have been suggested for the chemical control of molecular electronic devices are impractical because of the large energy changes associated with bond breaking and reforming: these would result in unacceptably large amounts of energy being required for device operation. We have chosen to look in detail at a class of chemical reactions prominent in biological systems that, on energetic grounds, could produce a feasible device: tautomerization reactions of heterocyclic bases. In particular, we concentrate on a model reaction, the 4‐pyridinol/4(1H)‐pyridinone tautomerization, through which an aromatic pyridinol unit is converted into a π‐localized pyridinone unit. In these molecules the functionalities are arranged para, allowing the possibility that the molecules align in a solid phase in linear hydrogen‐bonded chains. The change in the π electronic structure associated with reactions of this type is quite large, as illustrated, for example, in the conversion of quinacridone, a brightly colored pigment, to quinacridol, an uncolored species with strong UV absorption. Our primary purpose is to calculate energy changes and reaction barrier heights to see whether such tautomerization reactions could provide the basis for an operational chemically controlled molecular electronic device. We also consider, briefly, other required properties in a practicable device.

show abstract

Matrix isolation studies and ab initio calculations of the vibrational spectra of complexes of water with 3-hydroxypyridine

Cited by 38 publications

References 0 publications

Infrared spectra of tautomers and rotamers of 9-methylguanine. An experimental and theoretical study

Infrared spectra of tautomers and rotamers of 9-methylguanine. An experimental and theoretical study

Matrix-isolation and computational study of salicylhydroxamic acid and its photochemical degradation

Chemical Control of Tautomerization‐Based Molecular Electronic and Color Switches

Contact Info

Product

Resources

About